1. Field of the Invention
The invention relates to variable speed three-phase motors with intermediate rotor and inner rotor, and to a method for the production of the lamination packs of such three-phase motors.
2. Description of the Prior Art
A known variable speed three-phase motor of this kind features as intermediate rotor a non-magnetic metallic sleeve which is connected with the short-circuit rods of the main rotor or directly keyed to the drive output shaft. Such a motor is disclosed in my U.S. Pat. No. 3,749,949. This type of motor, however, has the disadvantage that eddy currents in the intermediate rotor lead to a buildup of heat in the three-phase motor, through which its maximum power output is limited.